Synthetic lubricating oil preparation



United States Patent 3,259,667 SYNTHETIC LUBRICATING OIL PREPARATION Donald H. Antonsen, Glen Mills, and Robert H. Johnson,

Swarthmore, Pa., assignors to Sun Oil Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Filed Oct. 21, 1963, Ser. No. 317,775 17 Claims. (Cl. 260-68315) This invention relates to the preparation of synthetic lubricating oils. having unusually high viscosity indexes and low pour points by the polymerization of certain straight chain alpha olefins by means of a particular type of catalyst system.

There are. various special applications for lubricating oils in which it is highly desirable that the oil employed have an especially high viscosity index, for example, a V.I. above 130. The oil also should have a low pour point, e.g., below -30 F., a high oxidation stability and lubricating properties that provide good wear characteristics. One such application is in the lubrication of jet aircraft wherein conditions of both'low and'high temperature may be encountered. Other special applications in which lubricants having such characteristics are desirable are automatic transmission lubrication, high temperature hydraulic applications, brake fluids, instrument oils, gear lubricants, automatic power steering unit lubricants, electric motor bearing lubricants, greases and aerospace applications. Lubricating oils that can be derived from petroleum generally do not have the combination of properties desired for these special applications.

In copending application Serial No. 251,724, filed January 16, 1963, now abandoned, a process is described and claimed by which lubricating oils of high viscosity index and low pour point can be prepared. Products of this process are particularly suited for such special applications as mentioned above. The process involves polymerizing straight chain alpha olefins of the C -C range at a temperature of 0-50 C. using a certain type of catalyst prepared from three components and in the presence of certain types of solvents. following three components: (1) aluminum alkyl sesquichloride; (2) titanium tetrachloride; and (3) either an oxirane such as ethylene oxide or propylene oxide or a methyl alkyl ether such as .dimethyl ether or methyl propyl ether. The types of solvents suitable for use as the reaction medium comprise saturated hydrocarbons and various halogenated hydrocarbons such as chlorobenzene and tri chloroethane.

The present invention constitutes an improvement over the process of aforesaid application Serial No. 251,724 for preparing high quality synthetic lubricating oils. The process of the present invention is particularly adapted for preparing lubricating oils of high viscosity index and low pour point which have kinematic viscosities at 210 F. below cs; When the total lubricating oil product obtained from the polymerization that boils above 650 F. has a viscosity below 15 cs. at 210 F., it is more suitable for producing specialty oils of such types as mentioned above. than when such total oil product is above the 15 cs. level. Generally it is most preferable that the viscosity of the total lubricating oil product above 650 F. be in the range of 3-10 cs. at 210 F. The present process is capable of producing such oils while operating at high catalyst efhciencies.

According to the invention high quality synthetic lubricating oils are prepared by polymerizing C -C olefins in the subtantial absence of any added solvent as reaction medium. The starting reaction mixture is composed of the olefin monomer and the catalyst with little if any solvent. The catalyst is prepared from the same three types of components as the catalyst described in the afore- The catalyst is formed from the 3,259,067 Patented July 5, 1966 said application but in addition contains a fourth component, namely, a diene capable of chelating with a metal component of the catalyst. The diene is an essential component of the catalyst system, as otherwise in the substantial absence of any added solvent and of any diene in the catalyst system the oily polymer obtained has a viscosity considerably higher than is desirable for the intended uses.

The process of the present invention is carried out by adding to one or more straight chain alpha olefins of the C -C range the following components which combine to form the catalyst system: (1) an aluminum alkyl sesquichloride, e.g., aluminum ethyl sesquichloride; (2) TiCl (3) an oxirane or a methyl alkyl ether; and (4) a diene capable of chelating with a metal component of the catalyst. The order of addition of these catalyst compo nents to the monomer preferably is as named above. The reaction mixture contains substantially no added solvent as reaction medium. In some cases it may be convenient to add one or more of the catalyst components as a solution in a solvent such as hexane; but the amount of solvent thus included in the reaction mixture will not be substantial, being for example only 2-10% by volume of the olefin monomer charged. The reaction is carried out by stirring the reaction mixture at a temperature in the range of 0-50 C., more preferably 15-35. C., until no further polymerization occurs or until an undesirably slow rate of polymerizationis reached. The catalyst is then fully deactivated and removed from the hydrocarbons and the latter can be distilled to recover any unreacted monomer and to separate the polymeric product into fractions as desired. In view of the fact that substantially no solvent is used in the reaction system, recovery of solvent for reuse is avoided or minimized.

It is highly important for obtaining the best products in good yield that the components of the catalyst system be present in certain proportions. In the first place the aluminum alkyl sesquichloride and the titanium tetrachloride should be used in amounts such that the atomic ratio of A1 to Ti is in the range of 0.8-2.5 and more preferably 1.0-1.6. At AlzTi ratios below 0.8, the desired viscositytemperature characteristics of the product cannot be secured, while at ratios above 2.5 the viscosity-temperature characteristics for the oils are poorer and also there is a tendency to produce solid polymers. Secondly, it is highly important that the amount of oxirane or methyl alkyl ether employed in the catalyst system be such that the atomic ratio of O to Al is withina certain narrow range. This range is 0.421 to 0.821, and a preferred range is 0.50-0.75. Reduction of the O to Al ratio below 0.4

results in poorer viscosity-temperature characteristics for the product, while an increase of the ratio above 0.8 causes a low yield of product.

The amount of chelating diene used should be in the range of 0.1-3.0 moles per atom of titanium. The effect of the incorporation of diene in the catalyst system is to reduce the viscosity of the oil product. Enough of the diene is employed to reduce the viscosity of the total oil product that boils above 650 F. to below 15 cs. at 210 F. and more preferably below 10 cs. at 210 F; When the amount of diene is increased above 3 moles per atom of titanium, the catalyst efiiciency drops and the degree of conversion of the monomer is reduced to an undesirably low value. Generally it is preferable that the amount of diene be in the range of 0.1-1.0 mole .per atom of titanium. Based on the monomer employed in the reaction the proportion of diene incorporated in the catalyst usually is less than 0.5% by weight and preferably is of the order of 0.02-0.2%. The diene becomes combined with the other catalyst components through chelation and does not partake in the reaction as a monomer.

When the oxygen-containing organic compound used in preparing the catalyst is an oxirane, it should conform to the formula wherein R is either hydrogen or an alkyl group of 1-20 carbon atoms. The oxiranes preferred for use in practicing the invention are ethylene oxide and propylene oxide. However other oxiranes conforming to the foregoing formula can be used, such as the 1,2-epoxy derivatives of butane, n-pentane, isopentane, n-hexane, isohexanes, octanes, decanes, dodecanes, .cetane, octadecanes, etc.

When the oxygen-containing component of the catalyst system is a methyl alkyl ether, the alkyl group can be any of those specified above for the oxirane compounds. Examples are dimethyl ether, methyl ethyl ether, methyl propyl ether, methyl isbutyl ether, methyl hexyl ethers, methyl decyl ethers, etc.

The aluminum-containing component of the catalyst system must be a sequichloride, as the desired results cannot be obtained with either an aluminum dialkyl monochloride or an aluminum alkyl dichloride. The alkyl group in the sesquichloride can contain from one to ten carbon atoms and preferably is a straight chain alkyl group. The sesquichloride can contain branched chain alkyl groups such as isobutyl or isopentyl, although this is not preferred. Examples of suitable alkyl groups in the sesquichloride are methyl, ethyl, propyl, n-butyl, n-hexyl, n-octyl and n-decyl.

As previously stated the diene used in preparing the catalyst system is one which is capable of chelating with a metal component of the catalyst system. Chelation is believed to occur with the titanium atoms rather than the aluminum atoms. The capacity for chelation depends upon the diene having a structure such that the spacing between the double bonds in the molecule is within certain limits so that the metal atom (titanium) can become coordinated at each double bond position. There are various types of dienes that Will provide such structure and hence are capable of chelating into the catalyst system. These are listed in Table I as Types A, B and C and are defined therein with several subtypes for each. Type A constitutes conjugated dienes, any of which are capable of chelating regardless of Whether the double bonds occur in rings or chains. Type B consists of dienes in which the bonds have 1,4-spacing and at least one double bond occurs in a ring. As used herein the term 1,4- spacing means that one carbon atom occurs between a carbon atom adjacent one of the double bonds and a carbon atom adjacent the other regardless of where the latter two carbon atoms are situated in the molecule. Type C consists of dienes wherein the double bonds have 1,5-spacing, at least one of the double bonds is in a ring and the two double bonds have a cis relationship to each other. As used herein the term LS-spacing means that two carbon atoms occur between a carbon atom adjacent one of the double bonds and a carbon atom adjacent the other double bond regardless of where the latter two carbon atoms are situated in the molecule.

TABLE I.TYPES OF CHELATING DIENES Type A.--Cnjugated dienes:

(1) With both double bonds in a chain. (2) With both double bonds in a ring. (3) With one double bond in a chain and one in a ring. (4) With the double bonds in separate rings. T yp e B.I,4-dienes with at least one double bond in a ring.

(1) With the other double bond in a chain. (2) With the other double bond in another ring. (3) With both double bonds in the same ring.

Type C.-1,5-dienes with at least one double bond in a ring and the double bonds having cz's-relationship to each other:

(1) With the other double bond in a chain. (2) With the other double bond in another ring. (3) With both double bonds in the same ring.

Specific examples of dienes of Types A, B and C and the various sub-types thereunder are given in Table II along with the structural formulas for the dienes named. Besides the dienes named in Table II there are many other dienes which are capable of chelating with a metal component of the catalyst provided that they conform to the classification of operative dienes set forth in Table I. Also halogen-substituted dienes of the structures specified in Table I are equally capable of chelating with the catalyst and can be considered as equivalent to the diene hydrocarbons for purposes of the present invention.

TABLE II.-EXAMPLES OF CHELATING DIENES Type Specific Diene Structure A1- Butadiene C=CC=C i A-1 Isoprene O=C-C=C A- 2,4-hexadiene CC=C-C=CC f r A1 2,4-dimethy1-1,B-pentadiene CC=C-C=O A-2 cyclopentadiene Q A2- 5-methyl-1,3-hexadiene C A2 1,3-0ctadiene Q A-2. 4-penty1-1,3-cyclobutadiene C-CC-CC A-2 Bicyclo-[4,4,0]-1,3-decadiene V A3. l-vinyl-cyclohexene V A3 2-ethylidene-cyclohexene-. =CC

A-3 2-vinyl-[4,4,0]-decene-1 C=C A-4 1,1-dicyclopentene A4 Bicyclo-[4,4,0]-decadiene-1,8

TABLE II-Continued TABLE IIOontinued Type Specific Dlene Structure Type Specific Dlene Structure 5 A4 2,3,4,5,9,10,1l,13-octahydro- C2 l,4,7,8,9,l0-hexahydrobenzonaphthene. naphthalene. l

C-2 2,3,4,6,7,8,9,10,l2,13-decahydroanthacene.

B1 2-vinyl-cyelohexene C=C O3 1,5-octadiene I ll B- L 3'ethylidene-eyclohexene. =C-C o-3- Bicyc1o[4.2.1]nona-2,6'diene B-1 p-Mentha-1,4(8)-diene O CC i P- (FOP/:0 In polymeriza-tions carried out heretofore utilizing Ziegler type catalysts a solvent has generally been employed as reaction medium even when the polymeric Blcyclohex-lz 'ene Q products are liquids. It would normally be expected that f .2 the omission of a solvent would materially reduce catalyst B-2- Spiro-(4.5)-deca-1.9-diene efficiency, inasmuch as catalyst activity tends to degradate with time and the rate of degradation is dependent upon catalyst concentration. The present process is an excepi tg g g i tion in that a solvent is not employed and yet the efiiciency is not substantially reduced. Referring again to the cat- ZMentaldiene (\A alyst system disclosed in application Serial No. 251,724 which system consists of the three types of components previously discussed, the use of such catalyst in polymerizing C C straight chain alpha olefins in the absence 12,7,8,9,1Mexahydm of a solvent generally gives an oil product having an unnaphthalene. desirably high viscosity. The total oil product boil ng above 650 F. generally has a kinematic viscosity consid- 40 erably above 15 cs. at 210 F. In contrast the present catalyst system, which includes a chelating diene as a B-3 1-methyl-2,5-cyclohexadiene fourth component, when used in the absence of a solvent will result in total oil products having viscosities in the desired range of 3l5 cs. at 210 F. While dienes normally would be considered as poisons for Ziegler type catalysts, their incorporation in the catalyst of the presl4'cyclooctadmne O ent process in the small proportions herein specified permits the production of oils having the desired viscosity 3 5 6 7 g h ah d without substantial loss in catalyst efliciency. The omisnaphthalene. sion of a solvent from the reaction system avoids themcessity of effecting solvent recovery and hence materially improves the economics of the process. The following examples illustrate the invention more B-3 Norbornadiene speclficany' K Example I A series of runs was made in a stirred reactor to show z the effect of isoprene in various concentrations in the C svmylcyclopentene l C 0 catalyst system on the polymerization of octene-l. In 0 each run the reactor and the octene-l were carefully dried v before use. The reaction mixture was prepared by adding l the following materials to the reactor in the order named: 300 g. of octene-l; 6.6 ml. of a- 1.0 molar hexane solution I of aluminum ethyl sesquichloride; 5.3 ml. of a 1.0 molar C 1'm- Hthyl1dene cycloheptenem C C hexane solution of TiCl 3.3 ml. of a 1.0 molar hexane solution of propylene oxide; and isoprene in amounts to c-1 l-(3-eycloltexenyD-Z-cyclu- C=C provide various molar ratios of isoprene'to TiCl as shown pemyl-eihy-enein Table In. The atomic ratio of AlzTi Was 1.25 and C the OzAl ratio was 0.5 in all runs. The weight ratio of Limonene 06 starting monomer to TiCl was 300:1. Each reaction was carried out at 30 C. for a total time of 20 hours The catalyst was then deactivated by adding to the reaction C2 v r y mixture 4 g. of Na CO adding 5 ml. of water with thorough mixing and then filtering. The filtrate was topped to remove unpolymerized octene, and the ol mer splmu'mdeca'lg'dlene product was vacuum distilled to remove the din ier a'nd obtain trimer and higher polymers as residuum. This residuum constitutes the total oil product boiling above 650 F. at atmospheric pressure. Results for six runs, including one run in which no diene was used, are shown in Table III. The column entitled Percent Conversion represents the total weight percent of octene-l which was converted to higher molecular weight compounds including the dimers. The column entitled Percent Dimer represents the weight percent of dimer in the total polymer solvent and at a temperature in the range of 0-50 C. with a catalyst system formed from (1) an aluminum alkyl sesquichloride, (2) titanium tetrachloride, (3) an oxygencontaining organic compound selected from the group consisting of oxiranes having the formula product consisting of dimer plus higher polymers.

H H TABLE III Dimer-tree Oil Product Run N0. Mole Ratio Percent Percent IsoprenezTiCl; Conversion Dimer K.V.io0r. K-V-2I0F. V.I.

0 77. 4 12. 4 149. 2 22. 6 139 0. 3 79. 3 14. s 61. 0 10.7 144 0. 5 73. 2 20.1 61. 5 10.8 144 1. 0 70. 5 l6. 5 47. 1 8.73 143 2. 0 66. 6 19. 5 34. a 6.60 147 3. 0 55. 7 23. 35. 2 6.92 151 R1111 1 Shows that the Catalyst Without a chelating wherein R is selected from the group consisting of hydiene will effect a good conversion of the starting monodrogen and alkyl groups having 1-20 carbon atoms and mer but that the viscosity of the total oil product above ethyl alkyl ethers, in whi h the alkyl groups has 1-20 650' F. is considerably higher than is desirable for making arbon ato nd (4) a dien capable of chelating with the types of specialty oil products contemplated within a metal com onent of the catalyst system, the amounts the scope of the invention. The other runs show that the of the aluminum alkyl sesquichloride and titanium tetrainclusion of a chelating diene in the catalyst system results chloride being such that the atomic ratio of Al to Ti is in in the reduction of the oil product viscosity to a desired the ran f 0,8 2 5, th m nt of said oxygen-containing level. This reduction is achieved without too much ad organic compound being such that the atomic ratio Of verse effect on the efiiciency of the catalyst y R 0 to Al is in the range of 0.4-0.8 and the amount of said 2-4 show that little eifect on the percent conversion occurs di being in the range of 0.1-3.0 moles per atom of at isoprene to TiCl molar ratios up to 1:1. As the ratio titanium, and thereafter separating from the reaction is increased up to 3:1 a substantial decrease in conversion mixture olefin polymer of lubricating oil boiling range. can be observed but the catalyst still is reasonably efiicient. 2, Method according to claim 1 wherein the ratio of At ratios above 3:1 the activity of the catalyst drops to O to A1 i in the range of 05-07. inordinately low levels. The data indicate that it is 3, M th d according to claim 2 wherein the A1 to Ti generally preferable to operate at diene to TiCl molar tio i i the range of1.0-1.6. ratios not exceeding 1:1. The pour points for all of the 4, M th d according to claim 3 wherein th amount dimer-free oil products of Table III were less than F. f di i i th range of 0.1-1.0 mole per atom of titanium. Example H 5. Method according to claim 1 wherein said sesqui- A series of runs was made in the same manner as in 45 chloride is aluminum ethyl sesquichloride. the preceding example except that norbornadiene was 6. Method according to claim 1 wherein said organic substituted for isoprene as the chelating diene used in the compound is propylene oxide. catalyst system. The reaction product was worked up in 7. Method according to claim 1 wherein said organic the same manner, and the test results are shown in Table compound is ethylene oxide. IV. Data for the run from Table III in which no diene 0 8. Method according to claim 1 wherein said temperawas used is repeated for ready comparison.

ture is in the range of 15-35 C.

stantially similar,

TABLE IV Molar Ratio Dimer-free Oil Product Run No. Norbornadiene: Percent Percent TiCh Conversion Dimer K.V.10o=r K.V.210F. V.I.

0 77. 4 12. 4 149. 2 22. s 139 0. 5 74. s 13. 9 68.5 12. o 1. 0 71. 9 16. 1 4s. 0 9. 03 14s 2. 0 57. 4 21.1 44.1 s. 51 a. 0 53. 0 22. 7 34. s 7. 02 153 From these data essentially the same conclusions can be 9. Method of preparing a synthetic lubricating oil which drawn as discussedinthe preceding example. comprises contacting straight chain alpha olefin of the Example III C -C range in the substantial absence of an added 0 When Run No. 8 (dienezTiCh ratio=1.0) is repeated 65 q 811:1 p e an the ranlge of 1145 0. except that limonene is substituted for norbornadiene, subi 1 a ca ,3 Z; if C 2 i 2 stantially equivalent results are obtained for percent con- 3 i i a? lamum etrac on an version and the viscosity properties of the product. oxlrane avmg 0mm 3 When other dienes of the types specified in Table I are 0 used 1n place of isoprene or norbornadiene, or When other oxiranes or methyl alkyl ethers as herein specified are H H used in place of propylene oxide, analogous results are wherein R is selected from the group consisting of hyobtained. Likewise when other straight chain alpha drogen and alkyl groups having 1-20 carbon atoms and olefins are substituted tor octene-l, the results are sub- 7 (4) a diene capable of chelating with a metal component of the catalyst system, the amounts of the aluminum alkyl sesquichloride and titanium tetrachloride being such that the atomic ratio of A1 to Ti is in the range of 1.0-1.6, the amount of oxirane being such that the atomic ratio of O to A1 is in the range of 0.5-0.7 and the amount of said diene being in the range of 0.1-3.0 moles per atom of titanium, and thereafter separating from the reaction mixture olefin polymer of lubricating oil boiling range.

10. Method according to claim 9 wherein said oxirane is propylene oxide.

11. Method according to claim 9 wherein said oxirane is ethylene oxide.

12. Method according .to claim 9 wherein said diene is a conjugated diolefin.

13. Method according to claim 12 wherein said diene is isoprene.

14. Method according to claim 9 wherein at least one double bond of the diene is in a ring and the two double bonds are spaced in 1,4-relationship.

References Cited by the Examiner UNITED STATES PATENTS 3,108,145 10/1963 Antonsen 260683.15 3,206,523 9/1965 Antonsen 260683.l5

DELBERT E. GANTZ, Primary Examiner.

R. H. SHUBERT, Assistant Examiner. 

1. METHOD OF PREPARING A SYNTHETIC LUBRICATING OIL WHICH COMPRISES CONTACTING STRAIGHT CHAIN ALPHA OLEFIN OF THE C6-C12 RANGE IN THE SUBSTANTIAL ABSENCE OF AN ADDED SOLVENT AND AT A TEMPERATURE IN THE RANGE OF 0-50*C. WITH A CATALYST SYSTEM FORMED FROM (1) AN ALUMINUM ALKYL SESQUICHLORIDE, (2) TITANIUM TETRACHLORIDE, (3) AN OXYGENCONTAINING ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF OXIRANES HAVING THE FORMULA 